What’s most important is the way its mere presence on the ballot, combined with a well run campaign, has transformed public dialogue about marijuana and marijuana policy. The media coverage, not just in California but around the country and even internationally, has been exceptional, both in quantity and quality. More people knew about Prop 19 than any other measure on the ballot this year — not just in California but nationwide.

The debate is shifting from whether marijuana should be legalized to how. Public opinion polls in California consistently reveal that a majority of the state’s citizens favor legalizing marijuana. One “No on 19″ campaign spokesman admitted that even his own supporters were divided between those who oppose legalizing marijuana and those who favor legalization but were wary of either Prop 19′s specific provisions or the federal government’s threats to block it from being implemented.

Prop 19 both elevated and legitimized public discourse about marijuana. It’s the small but growing number of elected officials who endorsed Prop 19 or said they’d vote for it — and the increasingly frequent private expressions of support by candidates and elected officials who said they wished they could be public about their position. It’s the growing number of endorsements by labor unions, including SEIU California, and civil rights organizations, including the California chapter of the NAACP and the National Latino Officers Association.

The international attention, especially in Latin America, has been extensive. Mexican President Calderon and Colombian President Santos both criticized Proposition 19, pointing to it as evidence of inconsistency in US drug policy. But the possibility that Prop 19 might win did prompt both presidents to call for more open debate about legalization and other alternatives to current drug policy. Mexican diplomatic officials publicly castigated Prop 19 but privately said they hoped it would win. No one thought a victory for Prop 19 would instantly put the violent Mexican drug trafficking organizations out of business but everyone recognized that it would represent a major step forward toward ultimately legalizing marijuana on both sides of the border. And that most definitely would undermine the criminal organizations, who would lose their competitive advantage just as repealing national alcohol Prohibition eventually did away with the bootleggers.

“How great it would be for California to set this example,” former Mexican President Vicente Fox said in a radio interview last week. “May God let it pass. The other U.S. states will have to follow step.”

There’s now solid and increasing evidence that marijuana legalization is an issue that young people care about a lot — and that putting it on the ballot increases the chances that they’ll actually vote. Both major parties have no choice but to pay attention, especially when the political allegiances of young voters are very much up for grabs. Democrats correctly see the marijuana issue as bringing out more votes for them than for Republicans. Asked what would bring out young, first-time Barack Obama voters again, the chairman of the California Democratic Party, John Burton, responded with one word: “Pot.”

It’s notable, though, that Meg Whitman, the Republican candidate for governor in California, did not actively campaign against Prop 19, most likely because she did not want to alienate young voters who don’t identify as Democrats but who do feel strongly about legalizing marijuana. Younger voters across the political spectrum increasingly lean libertarian, especially on issues like marijuana. Both Democrats and Republicans will need to re-think this issue when Gary Johnson, the former governor of New Mexico who has championed marijuana legalization and “harm reduction” drug policies for other drugs, runs in the Republican presidential primaries next year, as he seems sure to do. First-time and other young voters may gravitate in substantial numbers toward his message — and all the more so if Ron Paul decides to hand off the baton to his younger ideological soul mate.

For those of us engaged in long term strategizing on marijuana law reform, the plan is the same as it would have been if Prop 19 had won: to put the issue to voters in states where public opinion polls show majority support for legalizing marijuana, and to introduce similar bills in state legislatures. Public support for legalizing marijuana now approaches or tops 50% not just in California but in a growing number of western states, including Washington, Oregon, Alaska, Colorado and Nevada — so it’s reasonable to expect ballot initiatives on the issue in those states in coming years. It’s too soon to say whether the issue will be back on the ballot in California in 2012 but at the very least we know that a bill to regulate and tax marijuana will be considered by the state legislature, just as one was earlier this year. And a flurry of similar bills can be expected around the country as state legislators, emboldened by Proposition 19 and rapidly increasing support nationwide for marijuana legalization, kick start the conversation in their own legislatures.

Meanwhile, Prop 19 already can claim one hard victory: Governor Schwarzenegger recently signed into law a bill that will reduce the penalty for marijuana possession from a misdemeanor to a non-arrestable infraction, like a traffic ticket. That’s no small matter in a state where arrests for marijuana possession totaled 61,000 last year — roughly triple the number in 1990. It’s widely assumed that the principal reason the governor signed the bill, which had been introduced by a liberal state senator, Mark Leno, was to undermine one of the key arguments in favor of Prop 19.

Demographics, economics and principle all favor the ultimate demise of marijuana prohibition. Over half of California voters under the age of fifty said they’d vote for Proposition 19, and likely did. The youngest voters are most in favor while the most elderly voters are the most opposed. Meanwhile, the economic arguments for legalizing marijuana — including both the savings from reduced spending on law enforcement and the revenues from taxing legal marijuana, will only grow more persuasive. Marijuana isn’t going to legalize itself, but momentum is building like never before among Americans across the political spectrum who think it’s time to take marijuana out of the closet and out of the criminal justice system.